Soundbox for talking machines



July 9, 1929. 5, MILES 1.720.425

SOUND BOX FOR TALKING MACHINES Filed Aug. 10, 1927 July 9, 1929. MlLEs 1.720.425

SOUND BOX FOR TALKING MACHINES Filed Aug. 10, 1927 Patented July 9, 1929.

UNITED STATES PATENT OFFICE.

HARRY IBENDA MILES, OF COBUEG, VICTORIA, AUSTRALIA.

SOUNDBOX FOR TALKING MACHINES.

Application filed August 10, 1927, Serial No. 212,095, and in Australia September 2, 1926.

This invention relates to the soundboxes of talking machines in which a stylus and stylus bar are attached to convey to a diaphragm vibrations received from the moving sound record.

In records of recent introduction the sound grooves have more amplitude than formerly and it has been found that the needle or stylus will sometimes jump under the influence of the vibrations and that the sound will be distorted and the record in jured by the abnormal movements of the stylus.

It is to provide a soundbox the stylus of which will readily adapt itself to the sound groove that my invention has been devised thereby protecting the sound groove from undue wear and enhancing the purity of the tone.

To this end I employ a sound-box in which the parts containing the vibratory mechanisms are delicately suspended on a spring or springs that are attached between the sound-box and a tone-arm and so placed as to radiate in a direction at right angles with the tone-arm axis. The springs are intended to permit the sound box to rotate about the tone arm axis under the influence of the moving record. Such would occur when the pressure of the stylus on the sound groove exceeds a certain limit, as when the stylus is traversing a part of a groove that is greatly amplified. The pressure of the stylus on the.

groove should be kept as nearly as possible at an even pressure and my invention contributes to this result in that it permits the sound-box to move about the axis of the tonearm as the pressure between the sound groove and stylus varies. Thus, when the stylus is traversing a greatly amplified sound groove it will tend to remain in the groove owing to the flexible way in which the soundbox is attached to the tone-arm.

Existing practice does not meet the needs of the moment which require a non-vibratory sound-box flexibly connected to the tone-arm and wherein the vibrations of the stylus should be absorbed solely by the stylus bar and diaphragm.

My improved soundbox can have no 13111.

eral play in respect to the tone-arm. but it is essential that it be capable of limited movement about the tone-arm axis in one direct-ion only, that is to say, in the direction of movement of the record. The spring or springs are so disposed that as the sound groove passes under the stylus the springs will flex under pressure from the groove, thus tending to keep the stylus regularly in the sound. groove and enabling the sound-box to ride therein with a minimum of wear and tear upon the walls of the groove.

In the accompanying drawings,

Fig. 1 is a perspective view, partly broken away, 01 a soundbox and the spring housing 6 on the back of the box attached to tone arm in axial alignment therewith,

Fig. 2 a plan view of the spring housing as applied to an angular tone-arm, and

Fig. 3 a perspective view oi? a sleeve. that enters the housing and to which the tone arm and spring or springs are secured.

An approved mode of carrying the invention into effect is to attach to the back plate Of the soundbox t a housing 5 having a rearward central opening through which a sleeve 6 easily comes, that is to say the clearance between the opening and the sleeve may be fairly ample. The sleeve 6 receives the tone arm 7 to which it is seen red by the set screw 8 and to the sleeve is attached the inner ends of the flat springs 9 the outer ends of which are secured to the housing 5. To provide adjustment means to the springs the outer ends of same may be slotted as shown in Fig. 3. The sleeve 6 will therefore float within the housing upon the springs 9.

The sound groove will he moved in the direction of the arrow, Fig. 2, and as the stylus traverses the groove the springs will slightly flex according to the obstacles encountered by the stylus and the soundbox will slightly rise and tall upon the springs thus tending to keep the stylus point regularly in the groove.

Instead of two springs one may be employed with one end connected to the housing and the other to the sleeve and through the sleeve to the tone arm, but I preferably use the two radial springs J in the way explained.

Thus, the sound-box including the vibratory means will be suspended upon the springs through the housing 5 while the tone arm is connected to the sound-box containing the springs 9 through the sleeve 6. The springs 9 curve from the housing to the sleeve and each may be in the form of a partial involute.

2 v p c Having now described my invention what I claim as new and desire to secure by Letters Patent is:

In sound reproducing mechanism, a tone- 5 arm, a sound-box floatingly supported with relation to said tone-arm, and heiically disposed springs interposed between said soundbox and tone-arm and having their respective end portions secured to said respective elements, said springs serving as the sole means of connection, and the sole means for limiting radial movement, between said elements.

In testimony whereof, I have signed my name to this specification at Melbourne, Australia, this 20th day of May 1927.

HARRY BENDA MILES. 

